A multiple or mass casualty incident can generally be defined as an emergency or disaster where the number of patients or victims exceeds or taxes available resources, or where resource access is restricted or limited or where resources have to be staged. In contrast to routine emergencies, efficiently responding to a mass casualty incident requires triage protocol and procedures for effectively allocating the limited resources.
Triage, from the French verb trier, means to sort, and is the foundation of mass or multiple casualty management. Traditionally, medical attention and transportation to a next level of care is given first to those with the most urgent conditions. While this is appropriate in circumstances when resources are available for the immediate care of all victims, this does not necessary utilize resources most effectively when resources are limited.
The goal in the most widely used methods of mass casualty triage is typically to “do the greatest good for the greatest number”. This goal is not very explicit. A more tangible and measurable goal is to maximize the saving of lives. Achieving this explicit goal requires the maximum utilization of transport and treatment resources in consideration of the timing and availability of those resources, the severity of the injuries of the victims, and their deterioration should care and transport to the next level of care be delayed as a result of resource limitations.
Accordingly, triage shall be referred to herein as an organized evaluation of all casualties to prioritize treatment and/or transport of the casualties. Further, triage includes the consideration for the availability and timing of treatment and transport resources.
When casualties are generated in large numbers, as in a mass casualty incident, local medical resources can easily be overwhelmed. The scene is often in chaos, and the response can be disorganized. As such, the efficient use of resources is compromised, with emergency response personnel left to do the best they can. There is no single, standard, or universal method of triage to support these efforts.
The triage method most widely recognized and used is known as “START,” which stands for “Simple Triage and Rapid Transport.” START, and its many close variations, categorizes patients into four groups: Immediates, Delayed, Ambulatory or Walking, and Expectant, which are differentiated at the scene through color coded tags. Red (Immediate) patients are those categorized as critically injured, those having problems requiring immediate intervention. These victims are given the highest priority for transport and treatment. Yellow (Delayed) patients are injured, requiring some degree of medical attention, but are not expected to die within the first hour if care is delayed. These victims would be transported once all the Reds have been moved from the scene. Delayed patients are not ambulatory, usually requiring a stretcher for transportation. Green (Ambulatory) patients are not critically injured, and can walk and care for themselves. Black (Expectant) patients are deceased, or have such catastrophic injuries that survival is not expected.
START, and its many variations, provides direction for emergency responders at the scene of an incident. START directs that anyone who can walk be tagged Green and collectively moved to a safe place. Next, remaining casualties are moved to a casualty collection area and rapidly assessed. If a casualty is not breathing, an airway is opened manually. If the patient remains apneic, they are tagged Black; if they begin breathing, they are tagged Red. Patients who are breathing and have a respiratory rate above 30 are tagged Red. If respiration is below 30, circulatory status is assessed. If capillary refill takes more than 2 seconds, the patient is tagged Red. If capillary refill takes less than 2 seconds, mental status is assessed. Patients who can follow simple commands, such as handgrips, are tagged Yellow. Patients who cannot follow simple commands are tagged Red. From the casualty collection area, patients are often then moved to a dispatch area, and later transported as resources provide.
Although START is a widely recognized triage system, it has several limitations. First, START does not consider resource availability in its process. Red tagged victims are transported first, for higher level treatment, regardless of the number of victims or the availability of transport and treatment.
Second, START does not differentiate the severity of victim injuries within its categories, and there can be a wide disparity of severity within a START category. Some casualties are categorized Immediate because of a single measure, and some due to multiple measures, yet all are grouped together, even if actual criticality substantially differs. For example, an unconscious victim is immediately classified as a Red. This patient might have only a mild concussion and might regain consciousness without intervention. Another patient might be unconscious, but also has severe respiratory problems and an accelerated heart rate. START makes no differentiation between these two even though the severity is strikingly different.
Third, START does not consider a patient's survival probability in making triage decisions. This leads to less than accurate prioritization, and a less than optimal resulting percent of survivability. For example, a Red tag victim with very little hope of surviving the trip to the hospital might be the first assigned for transport from the scene, possibly wasting valuable resources. Likewise, a Red tagged victim with very high survival probability might be sent first, even though another victim might benefit more from immediate transport.
Fourth, START does not consider the likely deterioration of victims remaining at the scene while other victims receive transport priority. A victim's survival probability is likely to decline if that victim has to wait at the scene, and this deterioration is victim and injury dependant. A serious limitation of START is that “saveable” Red and Yellow tagged victims might be left at the scene deteriorating while higher priority, but more critically injured victims, receive the limited transport and treatment resources.
Finally, START's goal is not measurable, and therefore not attainable. START's goal is to “do the greatest good for the greatest number.” This is well intentioned, but is not precise or explicit. An explicit, measurable goal, such as maximizing the saving of lives, lends itself to review and accountability. With the overlay of constraints of transport and treatment resources, achieving this goal becomes a more rigorous process.